In Japan recently the coastal area is often reclaimed by soft clayey soil due to difficulty in obtaining sand or deposition of dredged soil. A large variety in
properties of reclaimed soil bothers geotechnical engineers in decision of design values.
　A large amount of vertical drains was installed to reduce settlement at the offshore expansion project of the Tokyo International Airport. The paper describes the performance of vertical drains on ground by soft soil, analyzing data obtained at this project.